Electric time switch



A. FRIEDINGER ELECTRIC TIME SWITCH Filed March 12, 1930 Sept. 27, 1932.-

Inj I w a O -2 0 7 w 1.. Il JHM-. l Mu I. 1 Q F W O 3l 0 Patented Sept. 27,- 1932 UNITED STATES PATENT oFFicE ALBERT FRIEDINGER, F FUBSTENFELDBRUCK, NEAR MUNICH, GERMANY ELECTRIC TIME SWITCH lApplication led March 12, 1930, Serial No. 435,121, and in Germanyuly 18, 192B.

This invention relates to an electric time switch, in which the retarding 'means is` a dash pot. -The time switchaccording to the invention differs :from the time switches of known types in that the displacing of the air *L from the cylinder of the dash pot is not regulated by a valve or cock and that the adjusting of the piston into the switching position is not effected by controlled intermediate elements, but that the switching in of the curo' rent is obtained by the adjusting of the piston of the dash pot by means of a handle, the

A piston being mounted to actuate directly the interrupter contact and the period ofthefree u piston movement from the adjusting position up to the extreme position vor switching ofl l position being determined by the -clearance of the piston in the cylinder and by the weight of the piston. Itbecomes possible I ,o thereby to employ any commonly used manner of operating the switch by the selection of suitable handles and to select any desired adjusted position of the piston corresponding with predetermined time indications for g the return of the piston into the initial position or into the cutting out position, as also to permanently maintain the adjusted position of the switch and to thereby use the switch similar to any ordinary switch with so cutting out at predetermined times.

Several embodiments of the invention are illustrated by way of example in the accompanying drawing in which Fi l is a section on line I-I of Fig. 2

showing the base of the switch.

Fig. 2 is a central longitudinal section on line II--II of Fig. 1.

\ Fi 3 is an elevation of the top side of the 'switcln Fig. 4 is a cross section on line IV-IV of FigQl.v

Fig. 5 shows section.

Fig. 6 shows another form of construction of the dash pot.

Figs. 7, 8 each show onev form of construction-ot` thehandle for the operation of the switch.

1 designates the cylinder of the dash pot, 2

the piston, 3 the piston rod, 4 a head of the the dash pot in longitudinal piston rod, and 5 a ring of insulating material under the head 4. The cylinder 1 is closed at the-bottom end, and closed on the top by a cover 6. The switch'case consists of a base 7 and of a lid 8, both of insulating mate- 55 rial., The cylinder 1 is embeddedin the switch base 7 and secured in its position by a pipe clip 9. In the switch base the binding posts 10 and l1 for the two wires l2 and 13 are 1 embedded. The binding post 10 is fitted 60 with a Contact plate 14 embracing the piston rod 3 of the air pump like a fork. The opposite binding post 11 carries a resilient flap 15 oscillatably mounted on a bolt 16, an eX- tension of said flap engaging under the con- 35 tact plate 14 on the binding post l0 and is pressed against this contact plate 14 by the. action of its spring, so that the circuit is closed between the binding posts 10 and 11.

The contact plate l5 has an upwardly bent .70 nose 17, the insulating ring 5 on the piston road 3 resting normally on this nose 17 and on the contact plate 14. By gravit and by the action of the heavy mass 4 on t ie piston rod the contact iap 15 is downwardly os- 75 cillated and thereby separated from the contact plate 14 so that the circuit is interrupted between the binding posits 10 and 11. The nosel of the iap 15 is relieved at the slightest ascending movement of the piston of the 30 dash pot, so that this flap 15 is "pressed by lthe action of its spring against the contact plate 14 and the circuit is ,closed.

The lifting of the piston or'the circuit closing is effected according to the invention by means of a suitable handle, by which the iston is directly shifted and adjusted. The ree return movement of the piston into the initial orswitching-ofi' position is effected by the weight of the piston andV by a certain sup- 9 plemei'ital load of the heavy mass 4, and in that the piston is fitted in the cylinder with little clearance, so that the air displaced by the piston can be discharged only slowly through the gap between the piston and cylinder wall and through the bore in the cylinder cover6 through which the piston'rod extends, air being sucked in on the same way. The time which the free movement 0f thel piston requires from its extreme adjusted m0 position up to the initial position depends on the width of the clearance between piston and cylinder and upon the weight of the heavy mass 4 and may be selected as desired. If the piston has to be adjusted in intermediate positions, the time of movement 1s accordingly shorter. It is immaterial whether the cylinder is arranged so that by the handle the piston is lifted off the cylinder bottom or towards this cylinder bottom.

The handle for effecting the switching in movement of the piston may be of suitable types according to whether the piston has to be shifted only into one single adjusting position permanently the same, or whether different adjusting positions are desired and whether the adjusting position has to be constant or variable. According to construction and operation of the handle the piston correspondingly switches o either after a certain time or after a time to be selected within certain limits, or it remains in its position until operated again.

In the forms of construction shown 1n Figs.

1 to 11 a slidable element 19 is mounted in the cover plate of the casing 18 covering the dash pot, a bifurcated arm 2O of this slidable element extending under the head 4 of the piston rod 3, the other end of said slidable element, bent at right angles, projecting through a slot 21 of the switch cover 8. A knob 22 on the outer, end of the handle 19, moving over a scale 23 marked on the casing lid 8, serves for adjusting the slidable element 19, and through the same the piston 2 of the dash pot is adjusted to any desired switching position. The scale 23 indicates how much time the piston requires to move from the adjusted position into the switching off position. The slidable element is pulled back into the initial position directly after the adjusting of the piston, the piston moving however not` with the slidable element 19 as the bifurcated arm l2() engages loosely under the head 4 of the piston rod. Blade springs 24 on the slidable element 19 serve for securing the handle in the position adjusted on the scale 28. Depressions corresponding with the division lines of the scale and provided in the lid of the casing 18 serving to securely hold the spring in the adjusted position. If the switch' has to remain permanently switched in, the slidable element 19 is not pulled back, and its springs 24 securely hold it in the adjusted position in opposition to the weight of the piston.

In order to prevent the piston from suddenly jumping back at the adjusting owing to the little vacuum formed behind the piston, the cylinder 1 has on the upper end one or several longitudinal grooves 25 in its inner wall, the grooves being longer than the piston so that in highest position of the piston the suction air can escape through the grooves 25 and the bore inthe cylinder cover 6. Similar longitudinal grooves 26 on the other end of the cylinder serve to effect a rapid discharging of the air shortly before the piston has arrived in the switching off position, whereby the spark formation at the cutting out is avoided.

In order to prevent jumping back of the piston owingto the suction air also in all intermediatepositions of the piston, short longitudinal grooves 27 are arranged step-v wise between the extreme ooves 25 and 26, and the iston 3 has annu ar grooves 28, the' width o which is equal to the length of the longitudinal grooves 27, so that between every two annular grooves of the piston a longitudinal groove 27 is situated, and the air can, at` the beginning of the adjusting, pass more lrapidly between the annular grooves of the piston and the longitudinal grooves 27. The corresponding extreme positions are secured by the sliding lblade springs 24 of the slidable element 19.

The handle for operating the piston shown in Fig. 7 is like a push button. The push button 29 acts upon an elbow lever 30, the inner arm of which has a bifurcated end 2O engaging under the head 4 of the piston rod. When the depressed push button is liberated, the bifurcated arm 2O is' suddenly returned into the initial position by the action of a spring 31., and the piston can freely move back. In this form of construction the switch serves only for switching in for a certain period, for instance for staircase lighting. For the push button a hand lever may be substituted.

The handle for operating the piston shown in Fig. 8 has the form of a rotatable handle. By means of the rotatable handle 33 an eccentric 34 is rotated, which shifts a slidable element 35 (similar to the slidable element 19 shown in Figs. 1 and 2) on a pin 37 in opposition to the action of a spring 36. IV'hen the rotation of the handle continues the slidable element is returned into the initial position without the piston. The rotatable handle can be secured in the part-rotations by means of springs, so that the switch can serve as permanent switch or for switching in for a certain time.

I claim:-

1. An electric time switch comprising in combination with the switch casing and the piston of the dash pot, a piston rod, a head on said piston rod, a lifting rod engaging under said piston rod head, a button arranged in said switch casing adapted to act on said lifting arm, and a spring on said lifting arm adapted to return said lifting arm into its initlal position and to liberate thereby this piston for the return movement.

2. An electric time switch comprising in combination with the piston of the dash ot, a piston rod, a head on said iston rod, a lifting arm engaging under sai head, a handle on said lifting arm adapted to oscillate said lifting arm and lift said piston, and a.

spring on said lifting arm adapted to return said lifting arm into its initial position without said piston and to liberate thereby this piston for the return movement.

In testimony whereof I ax my signature.

ALBERT FRIEDINGER. 

